In coordination chemistry there are a variety of methods applied to find out the structure of complexes.One method involves treating the complex with known reagents and from the nature of reaction, the formula of the complex can be predicted.An isomer of the complex `Co(en)_2(H_2O)Cl_2Br`,on reaction with concentrated `H_2SO_4` (dehydrating agent) it suffers loss in weight and on reaction with `AgNO_3` solution it gives a white precipitate which is soluble in `NH_3`(aq).
The correct formula of the complex is :

Options

A. `[CoClBr(en)_2] H_2O`
B. `[CoCl(en)_2 (H_2O)]BrCl`
C. `[Co Br(en)_2 (H_2O)]Cl_2`
D. `[CoBrCl(en)_2]Cl. H_2O`

Answer

D

Explanation

Water present in ionisation sphere is absorbed by conc. `H_2SO_4`(dehydrating agent).If `Cl^(-)` present as counter ion then reacts with `AgNO_3` to give white precipitate of AgCl